It sounds to me like the problems with a "portable" AC or heat-pump. They are freestanding units that look a bit like a room air purifier and are similarly meant for a single, small room. These are something one might buy online or at retail with the idea that there is no installation. It is worse than a window unit because both heat exchangers sit inside the conditioned space, and only a temporary/portable ducting arrangement connects the "outside" loop to the outside. They are also low power because they plug into a regular 15/20A power outlet.
We bought such a portable AC unit as an emergency measure during an extended heatwave and wildfire smoke event in the past. We bought the better kind of unit that has intake and exhaust hoses for the "outside" loop. Astonishingly, there are even worse products on the market that lack an intake hose. So they, by design, draw conditioned air through the output loop and then through the exhaust hose! You can imagine how inefficient that is, to be pumping air out of the conditioned space and create a negative pressure across whatever other leaky paths can refill the room.
Our portable unit with intake and exhaust hoses still does not work very well and leaks a lot of outside air into the conditioned space, obviously reducing indoor air quality when used on those smoky days. We had to hack together a big intake filtration box to keep the smoke out by drawing the intake air through a set of MERV 12+ furnace filters. We also added fiberglass insulated sleeves to the air hoses, which improved thermal and noise comfort.
